Injection pump



2 Sheets-Sheet 1 E. HAHN INJECTION PUMP Filed May 6, 1941 Jime 22:1943.

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INJEWCTION PUMP Filed May 6, 1941 ,2 Sheetsx-Sheer, 2

Patented June 22, 1943 I 2,322,350 1 v mrncnon rumr- Erwin 1mm, Arbon,Switzerland, assignor to M Adolph Saurer, Arbon, Switleriand ApplicationMay 6, 1941, Serial No. 392,142

In Germany May 1940 2 Claims.

This invention relates to injection pumps and more particularly to fuelinjection pumps of the slide controlled type having an inclined edgeprovided on the plunger piston for regulating the delivery of the pump.this type are mown wherein all the elements of the pump including thecam shaft are lodged in a single piece casing, into which the pumpcylinder is introduced and pressed down from the side thereof situatedopposite the cam shaft, and wherein the pump plunger is pressed againsta cam actuated push rod by means of a spring disposed in a laterallyopen chamber of the casing, the push rod being guided in a borepenetrating with a constant diameter a partition wall between the camshaft and the laterally open spring chamber. When in an injection pumpof .this type the necessity arises, owing to a defect,

to replace one or more pump elements, or a spring, a push rod, or anyother part, the pump must be dismounted, removed from the engine andcompletely disassembled. -In order to replace any part lodged in thecasing, the cam shaft always must be taken ofLflrst. When a governor iscombined with the pump, this governor must be removed. In case aninjection timing device is mounted on the pump, it must also be removed.The change of any part of such a pump accordingly is expensive andresults in a. considerable loss of time, particularly when such a pumpdefect happens on a vehicle motor so that this latter remainsinoperative on the road until a replacement pump is on hand, or evenmust be salvaged.

There have been made eiforts to create pumps permitting an easy exchangeof parts. For example the pump casing was made in two parts,

the cam shaft and the push rod being lodged in Injection pumps of aseparate lower casing portion and the pump cylinders in an upper casingportion. In this case the replacement of a pump element can be effectedwithout disassembling the cam shaft and without removing the governorand eventually the inJection timing device, but the entire upper pumpblock must be dismounted. In

known pumps of this type the pump plungers remain in the lower casingportion when the upper block is removed, and when the block is to beassembled again, the pmnp cylinders in this block must be lowered,against the action of all retracting springs, over the plungers looselyheld in the lower casing portion. Owing to the difliculty ofassembling-the pump in this manner, a replacement'of a pump element on avehicle motor on the road is not possible with such a type of pump.It-has also been proposed to render the connection between the plungerand the push rod accessible from the side-so that the plunger can bedisconnected and removed with the cylinder without disassembling the camshaft or parts of the casing, but in known constructions of this type itis not possible to remove the retracting springs or the push rodswithout disassembling the casing or removing the cam shaft.

According to further known pump designs, in which asimple replacementoi. pump elements has been aimed at, the difierent parts including theretracting spring for the plunger and the toothed control segments canbe pulled out upwardly. This construction has the disadvan tage that thediameter of the bore in the casing in which the pump assembly isintroduced from above, must be larger than the diameter of the springand of the toothed segments. Accordingly, complicated packings on alarge circumference must be used, and soft packing material is requiredfor making radial joints, as well as hard packing material for the axialjoints.

Mounting of such pump elements therefore requires great care.

The object of the present invention is the provision of an injectionpump of the above mentioned type in which the pump elements can bereplaced in extremely simple manner without requiring extensivedisassembling operations and without presentingthe mentioneddifficulties of known pump constructions for reassembling the packingsand correctly resetting the pumpelements. In the pump according to theinvention it is possible to loosen the connection between the springserving for retracting the pump plunger and the plunger through thelateral opening without rotation of the plunger, so that the plunger andthe cylinder can be dismounted from the side opposite the cam shaft, andall other parts such as retracting spring, spring cups, regulatingsleeve, toothed segment and push member can be taken oil? through thelateral opening. In this manner a replacement can be effected in avehicle motor on the road without any risk, and without requiring theremoval of the injection pump from the motor. The pump casing is made ina single piece without any separate portion; in the same casing there.are lodged all the pump elements together with the cam shaft, and thepump cylinders are introduced from the side of the casing opposite thecam shaft.

. The accompanying drawings illustrate several practical embodiments ofan injection pump according to the invention.

this connection is'realized by means of a lower .spring abutmentcomposed of two parts. The

- lower end oi. the spring is supported by an up- Fig. 3 is 'ahorizontal section along the line III-11]: f F18. 2.

Fig. 4 is a horizontal section along the line' IV-IV of F18. 1.

Fig. 5 is a perspective view in section showing an auxiliary device usedin the dismounting operation.

Fig. 6 is an axial section of a modified detail part oi the pump.

Fig. 7 is a transverse section along the line is made of a single pieceand contains all the elements of the pump. A lower chamber la of thecasing contains the cam shaft 2 having a cam 3 cooperating with the camfollower 4 carried by the journal 5 supporting the push member 6. Thispush member is slidably guided in a bore lb of a partition Ic separatingthe chamber la from an upper chamber Id. The push member 8 carries apressure screw 8 adjustably secured thereto by means of a counter nut I.The pump plunger 9 tightly fitting into the pump cylinder I9 isconstantly urged toward the pressure screw 8 of the push member by meansof a retracting spring H. A regulating sleeve l2 surrounds the cylinderl0 and is provided with teeth i3 meshing with a rack ll slidably guidedin the casing I. Movement of the rack transversely to the axis of theplunger 9 causes a movement of rotation of the sleeve l2. The lower endof this sleeve is provided with axial recesses l5 engaging a driver onthe plunger 9 capable of vertically moving with the plunger andtransmitting rotation from the sleeve I2 to the plunger. 7

The upper end of the plunger 9 is provided per cup 29 on which thespring bears directly, and by a lower disc 3| provided with a radialslot 39 and carried on a shoulder of a collar 39 formed on the plungerrod 32. This collar bears on the pressure screw 9 carried by the pushmember .6. The upper end of the retracting spring II is maintained in aspring washer 34 hearing against the casing l and at the same timepreventing-an axial displacement of the regulating sleeve l2. 4

The inner diameter D1 of the regulating sleeve l2,'as well asthediameters D: and D: of the bore in the casing i into which is insertedthe pump cylinder ID are at least equal or greater than the greatestdiameter of any member forming a part of the pump plunger, that is atleast equal or greater than the diameter of the driver ii. In thismanner it is possible, after having detached the connection between thespring ii and the pump plunger 9, to pull this latter together with thecylinder i9 upwardly across the bores D1 and D2 and remove these partsfrom the pump casing i. To facilitate this removal, the upper end of theplunger '9 is preferably provided with a threaded 'hole 35, so that ascrew bolt can be engaged in this hole and the plunger 9 and thecylinder l0, owing to the driver It bearing against the lower end of thecylinder,

pulled easily out of the casing by means of this bolt.

For disconnecting the spring I I from the pump plunger 9 preferably anassembling sleeve 26 shown in Fig. 5 is used, adapted to take up thepressure exerted by the spring so as to relieve the plunger from thespring action. This sleeve 36 has the shape of a horseshoe in plan viewand The inner distance H between the two flanges 21, 38 is slightlygreater than the shortest distance between the two spring cups 29 and 34when the spring is compressed. Both springs cups 34 and 29 are providedwith small rims 39 and 40, respectively, the rim l0 projectingdiametrically beyond in known manner with an inclined regulating edgei'l permitting, upon a rotation of the plunger, to vary the amount offuel delivered by the pump. Fuel arrives in the pump chamber Hi from thesuction chamber 20 through the ducts l9 opened by the plunger 9 when itis in its lower position. A valve body 2|, containing the pressure valve22 applied on its seat by aspring 23,

-is tightly fitting upon the pump cylinder l9. The

ing spring II for the pump plunger 9 is con-. I

nected to the plunger by means of a connection i which can be easilydetached through the window 21. In the example according to Figs. 1 to 4the slotted disc 3i, and when the spring is compressed to its smallestlength, the flanges 31 and 38 can be introduced over these rims.

The removal of a pump element is obtained in the following manner: Thecover 28 is removed from the lateral opening 2'! of the chamber Id.First the pressure plug 24 is loosened and the pressure valve body 2|together with the valve 22 is pulled out. Then the cam shaft 2 is turnedto bring the push member 6 and the plunger 9 to their highest position,in which the retracting spring is compressed to its smallest length. Theassembling sleeve 36 can now be pushed with its flanges 31 and 38 overthe rims 39 and 40 of the spring cups 29 and 34. The cam shaft 2 isturned back to return the push member 6 to its lowermost position. Thespring, H, the plunger 9 and the spring cup 29 are maintained in theirupper position by the assembling sleeve 36. A screw bolt is now screwedinto the threaded hole 35 on the upper end of the plunger, and thisplunger is then first pushed downwardly by means of this bolt, tothereby release the disc 3i provided with the slot 29. Now this disc 3iforming the connection between the spring II and the plunger 9 can beremoved laterally, so that the collar of the plunger rod 32 is free tomove upwardly, and the plunger can be pulled upw wardly by means of thescrew bolt until the driver l6 abuts against the lower side of the pumpcylinder It. By a further pulling action exerted on the plunger, thecylinder I is also pulled upwardly by the intermediary of the driver l6and removed from the pump casing I through the bore D1 in the regulatingsleeve l2 and the bores D2 and D3 in the casing I.

arm 41 is provided so that a single groove 46 is i required in theregulating sleeve l2 and in the The introduction of a new pump cylinderand plunger is effected in the same easy way. Care must be taken onlythat the driver l6 engages correctly in the recesses l5 of theregulating sleeve I2. When the pump plunger and the cylinder are to beexchanged, the other parts, such as the regulating sleeve l2, the springspring cups 29 and 34, and the assembling sleeve 36, as well as the pushmember 6 can remain in their respective places. But if one of thesemembers must be exchanged, it can be removed from the casing l withoutdifliculty through the lateral opening 21 and replaced by a new part.All the replacement operations can be carried out without removing theinjection pump from the motor and without any supplementarydisassembling work, and for this reason these operations can be effectedin an extremely short time and without any risk.

In the modification of the connection between the retracting spring Hand the pump plunger 9 according to Figs. 6 and 7, the spring abutmentis again made in two parts, a closed annular disc 4|, and a slottedwasher 42 formed by a wedge of horseshoe shape bearing on the collar 33of the plunger rod 32. In order to facilitate the removal of the springwasher 42, it is advantageous to recess the rod 32 just above the collar33, so as to form a shoulder 43, which acts as abutment for the washer42 when the disc H is raised and urges the washer laterally away fromthe disc 4 I, so that it can easily be gripped.

Figures 8 and 9 show a further modified connection between the pumpplunger 3 and the retracting spring II. In this modification the springdisc is formed by a single part 44 provided with a slot 30 and with aspring supporting rim portion from which two segments are cutlofi' at45. At these two places where the rim is cut'ofl, the spring ll projectsdiametrically beyond the slotted disc 44, so that the spring itself canbe gripped and raised, whereaiter'the disc 44 can be pulled outlaterally.

In the modification according to Figs. 10 and 11 the upward removal ofthe plunger is realized by the fact that the bore D1 of the regulatingsleeve l2 and the bore D2 of the casing I are provided with a groove 46engaging the driver 41 on the II with the plunger rod 32. In thisexample a single driver pump casing for removing the plunger. But therecould be provided several driver arms and several grooves. The diameterD; of the upper cylinder portion must be so large, in this arrangement,that the shoulder 26 of the cylinder ill forms a tight joint at theupper end of the groove 46. In Fig. 10 an assembling sleeve 36 is shownin dash and dot lines, which is adapted to release. the plunger from thepressure of the spring.

I claim:

1. An injection pump comprising a single piece casing formed with abore, a pump cylinder removably inserted in said bore,- a pump plunggreciprocable in said cylinder, said casing being provided with a chamberhaving a lateral opening, a'plunger retracting spring disposed in saidchamber and detachably connected with said plunger, said springconnection including an abutment shoulder on the plunger, a radiallyslotted disc loosely engaged on the plunger and resting on saidshoulder, an annular spring cup carried by said disc to support one endof said retracting sprin and a spring cup supporting the other end ofthe retracting spring, said two spring cups having annular rim portionswhereby an auxiliary sleeve member may be inserted through said lateralopening to engage the rim portions of said spring cups and relieve theplunger from spring pressure to permit removal of said slotted discengaged on the plunger and withdrawal of said plunger and pump cylinderfrom said bore in the Pump casing.

2. An injection pump comprising .a single piece pump casing formed witha bore, a pump cylinder removably inserted in said bore, said casingbeing provided with a chamber having a lateral opening, a pump plungerreciprocable in said cylinder,

the outer end ofthe plunger extending into said chamber, an abutmentshoulder on the outer end of the plunger, a radially slotted discloosely encally beyond the periphery of the'slotted disc whereby saidspring unit can be engaged by its projecting portions to relieve theplunger from spring pressure and permit removal of said slotted discfrom theplunger and withdrawal of said plunger and pump cylinder fromsaid bore in the pump casing.

' IRWIN HAHN.

